1. Field of the Invention
The present invention relates to carburetors and, more particularly, to a throttle valve linkage for use with a multi-carburetor assembly comprising a plurality of carburetors disposed between engine cylinders arranged in a pair or pairs, as in the case of V-type engine for two-wheeled vehicles, each carburetor being provided for one of the cylinders.
2. Description of the Prior Arts
The type of engines has been known in the field of two-wheeled vehicles which has a plurality of cylinders arranged in a row extending transversely of the longitudinal axis of the vehicle. In this type of engines, carburetors are arranged also in a row transverse to the longitudinal axis of the vehicle so that the throttle shafts of these carburetors are disposed on a common axis. In this case, therefore, there is no substantial difficulty in designing and constructing a throttle valve linkage for operating the throttle valves of all carburetors similarly and in synchronization.
This type of engine, however, inevitably has a large length in the direction transverse to the longitudinal axis, i.e., the running direction, of the vehicle and makes the operation of the two-wheeled vehicle difficult.
Under this circumstance, in recent years, two-wheeled vehicles have been put into use which are designed to have V-type engines in each of which a plurality of cylinders are arranged in V-shape as viewed from lateral side of the vehicle. In this type of engine, a multi-carburetor assembly comprising a plurality of carburetors provided each for one cylinder, are disposed in a limited space between the cylinders arranged in a pair or pairs. The multi-carburetor assembly is arranged such that the direction of suction of air by a first carburetor associated with a first cylinder is opposite to that of a second carburetor associated with a second cylinder and the throttle valves of these carburetors are not arranged on a common axis but are mounted on separate throttle shafts having parallel axes spaced from each other. The two throttle shafts are connected to each other by means of a wire which is wound at both ends thereof in opposite directions around two throttle shafts. One of the throttle shafts is operatively connected to an accelerator adapted to be operated by the driver. As the driver operates the accelerator for accelerating the vehicle, the throttle shaft operatively connected to the accelerator and, hence, the throttle valve carried by this throttle shaft are rotated in one direction. Simultaneously, the rotation of this throttle shaft is transmitted to the other throttle shaft through the wire to rotate the other throttle shaft and the throttle valve in the direction opposite to the direction of rotation of the first-mentioned throttle shaft and throttle valve. The first-mentioned throttle shaft and throttle valve directly operated by the accelerator will be referred to as "driving throttle shaft and throttle valve," while the throttle shaft and throttle lever driven through the wire will be referred to as "driven throttle shaft and throttle valve," hereinafter.
The conventional wire-type throttle linkage between the driving and driven throttle shafts involves the following problems. Namely, this conventional linkage cannot provide good synchronism and similarity of operation of two throttle valves. More specifically, the operation of the driven throttle valve tends to be lagged behind the operation of the driving throttle valve particularly in a part throttle engine operation range. In addition, the wire is undesirably elongated in a relatively short period of time due to the tension applied thereto and deteriorates the synchronism and similarity of operations of the two throttle valves.
The prior art throttle valve linkage which utilizes a wire is not satisfactory because of the problems discussed above, although the prior art linkage can be installed in a limited space.